JP2007305219A - Optical disk device and optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress increase of jitter during second recording. <P>SOLUTION: An optical disk device recording data in a re-writable optical disk records data by irradiating with a laser beam in which recording power is superimposed on erasing power. Erasing power during initial recording is increased more than erasing power during recording on and after second time, an erasion ratio during initial recording is increased. Or erasing power during initial recording is increased, while the recording power during initial recording is decreased more than recording power during recording on and after second time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disk device, and more particularly to power control when data is recorded on a rewritable optical disk.

  2. Description of the Related Art Conventionally, there has been proposed a technique for improving data overwrite characteristics in an optical disc apparatus that records data on a rewritable optical disc such as CD ± RW, DVD ± RW, or DVD-RAM.

  In the following Patent Document 1, in the phase change type optical recording medium, the jitter increases in the second recording after the first recording after manufacturing, and then decreases as the recording is repeated. In view of this, it is described that recording is performed at least three times in advance, that is, performing at least two times of overwrite to reduce jitter and reduce reading errors in subsequent recording. The reason why the jitter increases in the second recording from the first recording and the reason why it decreases again in the subsequent overwriting is as follows. And a recording mark obtained by overwriting a predetermined position where the recording mark is recorded, the phase state of the recording layer corresponding to the recording state, the atomic arrangement in the phase state of the recording layer corresponding to the unrecorded state, etc. It is described that there is some difference, and this difference is gradually reduced by repeating the overwrite, and after the several overwrites, there is no difference from the initial state.

  Further, in Patent Document 2 below, in the phase change optical recording medium, in order to reduce the time required for recording in the unrecorded area and to reduce jitter in that case, recording is performed in the unrecorded area of the recording layer. Vw / Vo> 1 and 0.3 <Pew / Peo <, where Vw is the linear velocity used when performing, Pew is the erasing power, Vo is the linear velocity used during overwriting, and Peo is the erasing power. 1 is described.

  Patent Document 3 below describes that when recording data in an unrecorded area of an optical disc, the recording power is set smaller than when recording data in an already recorded area.

JP 2001-126265 A JP 2001-344663 A Japanese Patent Laid-Open No. 2003-233907

  However, in order to prevent the jitter from increasing in the second recording compared to the first recording, in the configuration in which the recording is performed at least three times in advance, it is necessary to perform the overwrite twice in advance. There is a problem that the time increases and the number of rewrites decreases.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to record data with high quality by suppressing a situation in which jitter increases in the second recording compared to the first recording. It is to provide an apparatus that can.

  The present invention relates to an optical disk device for recording data on a rewritable optical disk, in which data recording means for recording data by superimposing recording power on erasing power, and an area to be recorded on the optical disk is an unrecorded area And a control means for increasing the ratio of the erasing power to the recording power as compared with the case of the already recorded area.

  In one embodiment of the present invention, the control means increases the erasing power when the area to be recorded on the optical disc is an unrecorded area as compared to when the area is an already recorded area.

  In another embodiment of the present invention, the control means increases the erasing power and increases the recording power when the area to be recorded on the optical disc is an unrecorded area as compared to the recorded area. Reduce.

  The present invention also relates to an optical disk device for recording data on a rewritable optical disk, the data recording means for recording the data by superimposing the recording power on the erasing power, and the first and subsequent recordings on the optical disk. And control means for increasing the erasing power as compared with the time of recording.

  The present invention also relates to a rewritable optical disc on which data is recorded by a laser beam irradiated with an erasing power and recorded with the erasing power, and the erasing power at the first recording and the second and subsequent recordings. Information on the erase power at the time is recorded in a predetermined area, and the erase power at the first recording is larger than the erase power at the second and subsequent recordings.

  According to the present invention, when data is recorded in an unrecorded area, or by increasing the erasure ratio at the time of initial recording, the difference in irradiation energy between the recorded portion and the unrecorded portion after the initial recording is suppressed. In the case of recording data on the recording medium, it is possible to suppress the increase in jitter during the second and subsequent recordings and to record the data with high quality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall configuration diagram of an optical disc apparatus according to the present embodiment. A rewritable optical disk 10 such as DVD ± RW or DVD-RAM is rotationally driven by a spindle motor (SPM) 12. The spindle motor SPM 12 is driven by a driver 14, and the driver 14 is servo-controlled by a servo processor 30 so as to have a desired rotation speed.

  The optical pickup 16 includes a laser diode (LD) for irradiating the optical disk 10 with laser light and a photodetector (PD) that receives reflected light from the optical disk 10 and converts it into an electrical signal, and is disposed opposite to the optical disk 10. . The optical pickup 16 is driven in the radial direction of the optical disk 10 by a thread motor 18, and the thread motor 18 is driven by a driver 20. The driver 20 is servo-controlled by the servo processor 30 similarly to the driver 14. The LD of the optical pickup 16 is driven by a driver 22, and the driver 22 is controlled by an auto power control circuit (APC) 24 so that the drive current becomes a desired value. The APC 24 and the driver 22 control the light emission amount of the LD according to a command from the system controller 32. Although the driver 22 is provided separately from the optical pickup 16 in the figure, the driver 22 may be mounted on the optical pickup 16.

  When data recorded on the optical disk 10 is reproduced, a laser beam of reproduction power is irradiated from the LD of the optical pickup 16, and the reflected light is converted into an electric signal by the PD and output. A reproduction signal from the optical pickup 16 is supplied to the RF circuit 26. The RF circuit 26 generates a focus error signal and a tracking error signal from the reproduction signal and supplies them to the servo processor 30. The servo processor 30 servo-controls the optical pickup 16 based on these error signals, and maintains the optical pickup 16 in an on-focus state and an on-track state. Further, the RF circuit 26 supplies an address signal included in the reproduction signal to the address decoding circuit 28. The address decoding circuit 28 demodulates the address data of the optical disk 10 from the address signal and supplies it to the servo processor 30 and the system controller 32.

  One example of the address signal is a wobble signal. A wobble signal is wobbled by a modulated signal of time information indicating the absolute address of the optical disc 10, and the wobble signal is extracted from the reproduction signal and decoded to decode the address data (ATIP ) Can be obtained. Further, the RF circuit 26 supplies the reproduction RF signal to the binarization circuit 34. The binarization circuit 34 binarizes the reproduction signal and supplies the obtained signal to the encoding / decoding circuit 36. The encode / decode circuit 36 demodulates the binary signal and corrects errors to obtain reproduction data, and outputs the reproduction data to a host device such as a personal computer via the interface I / F 40. When the reproduction data is output to the host device, the encoding / decoding circuit 36 temporarily stores the reproduction data in the buffer memory 38 and outputs it.

  When recording data on the optical disk 10, data to be recorded from the host device is supplied to the encode / decode circuit 36 via the interface I / F 40. The encode / decode circuit 36 stores data to be recorded in the buffer memory 38, encodes the data to be recorded, and supplies the data to the write strategy circuit 42 as modulated data. The write strategy circuit 42 converts the modulation data into a multi-pulse (pulse train) according to a predetermined recording strategy, and supplies it to the driver 22 as recording data. Since the recording strategy affects recording quality, optimization is performed prior to data recording. That is, test data is test-written by changing the recording strategy in a predetermined test area of the optical disc 10, and the test data that has been test-written is reproduced and its signal quality is evaluated. Then, an optimum recording strategy is selected based on the evaluation result. The laser light whose power is modulated by the recording data is irradiated from the LD of the optical pickup 16 and the data is recorded on the optical disk 10. More specifically, data is recorded with a laser beam in which recording power is superimposed on erasing power, and data is recorded in the recording power area while erasing data already recorded in the erasing power area (overwrite recording). . After recording the data, the optical pickup 16 reproduces the recorded data by irradiating a laser beam with a reproduction power, and supplies it to the RF circuit 26. The RF circuit 26 supplies the reproduction signal to the binarization circuit 34, and the binarized data is supplied to the encode / decode circuit 36. The encode / decode circuit 36 decodes the modulated data and collates it with recorded data stored in the buffer memory 38. The result of the verification is supplied to the system controller 32. The system controller 32 determines whether to continue recording data or execute a replacement process according to the result of verification.

  The system controller 32 controls the operation of the entire system, and particularly performs OPC (OPtimum Power Control) prior to recording and optimization of the recording strategy. In OPC, test data is trial-written in a test area of the optical disc 10 while changing the recording power stepwise, and the test data that has been trial-written is reproduced and its β value, γ value, modulation factor, error rate, etc. are measured. . Then, the recording power at which the reproduction signal quality such as the error rate becomes a desired value is selected and set as the optimum recording power Po. The system controller 32 controls the driver 22 so that the selected recording power Po is obtained. In the optimization of the recording strategy, test data is test-written by changing the recording strategy for each type of the optical disc 10, the test data is reproduced, the error rate is measured, and each recording strategy is evaluated according to a specific evaluation standard. .

  In such a configuration, in the case of the rewritable optical disc 10, the jitter is increased in the second recording, that is, the first overwrite recording, as compared with the first recording as described above. The reason for this is that, in the prior art, a recording mark that is first recorded at a predetermined position in a completely unrecorded state after manufacturing, and a recording mark that is obtained by overwriting the predetermined position at which the recording mark is recorded. This is because there is some difference in the phase state of the recording layer corresponding to the recording state and the phase state of the recording layer corresponding to the unrecorded state, such as atomic arrangement.

  FIG. 2 shows the relationship between the recording strategy for recording data and the formed recording marks. The recording strategy is multipulse, and has a reproduction level, an erasing power, and a recording power as power levels. Reproduction power <erase power <recording power, and the recording power is composed of multiple pulses. The number of multi-pulses is set according to the data length of data to be recorded, and the multi-pulse width is adjusted to an optimum value. The erasing power is superimposed on the reproduction power, and the recording power is further superimposed on the erasing power, and new data is recorded with the recording power while erasing the already recorded data with the erasing power. It is assumed that the mark 100 and the mark 200 are recorded on an information track on the optical disc 10 at the time of initial recording with such a recording strategy. Next, it is assumed that the mark 300 and the mark 400 are overwritten on the same information track during the second recording (first overwriting). In this case, neither the mark 300 nor the mark 400 straddles the ends of the mark 100 and the mark 200.

  On the other hand, the mark 500 is overwritten on the same information track during the second recording. In this case, the mark 500 straddles the end of the mark 100. In such a case, the mark 500 includes both the recorded portion and the unrecorded portion, and the shape of the mark 500 is disturbed at the boundary between the recorded portion and the unrecorded portion due to a structural difference between the recorded portion and the unrecorded portion. There is a fear.

  As described above, the applicant of the present application increases the jitter in the second recording (first overwriting) from the first recording in the end of the mark 100 recorded in the first recording like the mark 500. Recording in the first recording is considered to be one of the causes, and even if recording is performed over the end of the recorded mark in the second recording, the increase in jitter is suppressed. The difference in structure between the recorded area and the unrecorded area is reduced. In order to reduce the structural difference, it is only necessary to reduce the difference in the laser power of the irradiated laser beam between the recorded part and the unrecorded part. The recorded part is irradiated with the recording power and the unrecorded part is irradiated with the laser beam with the erasing power. Therefore, the difference between the recording power and the erasing power may be reduced at the first recording. Based on such a technical idea, in the present embodiment, the ratio of the recording power and the erasing power, that is, the ratio of the erasing power to the recording power, at the time of initial recording and other than that, erasing ratio ε = (erasing power) / ( Change the recording power.

  FIG. 3 shows the change in the erase ratio with respect to the number of recordings. In the figure, the horizontal axis represents the number of recordings, and the vertical axis represents the erase ratio. In the first recording, that is, in the first recording on the unrecorded optical disk 10, the erasing ratio β is set. In the second and subsequent recordings, that is, in the first and subsequent overwriting, the erasing ratio is α smaller than β. In other words, only for the first recording, the erasure ratio is increased from α and data is recorded as β. Thereby, the structural difference between the recorded portion and the unrecorded portion at the end of the mark 100 in FIG. 2 is reduced, and even if the mark 500 is recorded in the second recording, the structural difference at the end of the mark 100 is reduced. Since the mark 500 is small, disorder of the shape of the mark 500 is suppressed, and an increase in jitter can be suppressed.

  Since the erasure ratio is defined as the ratio of the erasing power to the recording power as described above, in order to increase the erasing ratio at the initial recording, the erasing power at the initial recording is increased or the initial recording is performed. What is necessary is just to reduce recording power. Alternatively, it is sufficient to increase the erasing power at the time of the initial recording and reduce the recording power. In the present embodiment, a case will be described in which the erasing power at the first recording is increased.

  FIG. 4 shows a change in jitter when the second recording (first overwriting) is performed by variously changing the erasing power at the first recording. In the figure, the horizontal axis represents the recording power (mW) in the second recording, and the erasure ratio ε in the second recording is ε = 0.31. The vertical axis represents relative jitter. The recording power at the first recording is 23.5 mW, and the erasing ratio is changed by changing the erasing power at the first recording to ε = 0.21 (21%), ε = 0.39 (39%), ε = 0. .47 (47%). In any case, when the recording power in the second recording is increased, the jitter is reduced, and when the recording power is increased further, the jitter tends to increase. However, the erasure ratio ε of the first recording is 21%, 39%, The jitter decreases as it increases to 47%. In addition to the erase ratios of 21%, 39%, and 47% shown in FIG. 4, the applicant of the present application measured the jitter change by changing the erase ratio in increments of 2% from the erase ratio of 19% to the erase ratio of 47%. It has been confirmed that the jitter tends to decrease as the erase ratio increases.

  From this, it can be seen that by increasing the erasing power at the first recording, the jitter of the second and subsequent recordings can be reduced, and data recording with excellent recording quality can be achieved. In addition, in this embodiment, the erasing power is increased only at the time of the first recording, so that it hardly affects the number of rewrites and there is no possibility of deterioration of the number of rewrites.

  It should be noted that if the erasing power is increased too much, it approaches the recording power and data is recorded with the erasing power, so there is naturally an upper limit of the erasing power, and a range not exceeding this upper limit (recording layer The erasing power may be increased and adjusted with a power that does not heat the melting point above the melting point.

  Specifically, the erasing power adjustment method is as follows. That is, the recording power and the erasing power are usually β values, jitters, modulation factors, γ values, error rates, etc. obtained by trial writing test data with various recording powers in the test area of the optical disc 10 and reproducing the test data. The optimum recording power Po is set based on the reproduction signal quality (OPC: Optimum Power Control). Then, the optimum erase power is set by Pe = ε · Po using a predetermined erase ratio ε. In the second and subsequent recordings, data recording is performed with the optimum recording power Po and optimum erasing power Pe set in this way. In the first recording, Pe is multiplied by a predetermined coefficient K (K> 1). Let Pe be the erasing power. As a result, data can be recorded with the erasing power increased only during the first recording. Of course, as a predetermined erase ratio ε, ε1 for initial recording and ε other than that are prepared (where 0 <ε <ε1 <1), and the erasing power is set by Pe = ε1 · Po only at the time of initial recording. It may be set.

  FIG. 5 shows a processing flowchart of the present embodiment. When the optical disk 10 is loaded, the system controller 32 first executes OPC to set the optimum recording power Po for the optical disk 10 (S101). That is, the optical pickup (PU) 16 is sought to the test area of the optical disc 10, test data is written by changing the recording power, the test data is reproduced, and its β value and modulation degree are measured. Then, the recording power at the target β value is set as the optimum recording power Po, or the upper limit recording power at which the gradient of the modulation degree becomes a predetermined value is multiplied by a constant to obtain the optimum recording power Po. After setting the optimum recording power Po, the system controller 32 reads the erasing ratio ε stored in the memory in advance or obtains the erasing ratio ε stored in the lead-in area of the optical disc 10 to obtain the optimum recording power Po. Is multiplied by ε to set the optimum erasing power Pe = ε · Po (S102).

  After OPC is executed and Po and Pe are set, user data is recorded in the user data area of the optical disc 10. At the time of recording, it is determined whether or not the current recording is the first recording (S103). If the recording is not the first recording but the second and subsequent recordings, that is, overwrite, Po and the values set in S101 and S102 are determined. Data is recorded by applying Pe as it is (S105). On the other hand, in the case of the first recording, the system controller 32 reads the coefficient K (K> 1) stored in the memory in advance, and multiplies Pe by the coefficient K to increase and adjust the optimum erasing power (S104). . After the erase ratio is increased by increasing the erase power, data is recorded with the optimum recording power Po and the erase power K · Pe (S105).

  Whether it is the first recording can be determined using the method disclosed in Japanese Patent Laid-Open No. 2003-233907. The detection circuit detects whether or not the RF component is included in the reflected light from the optical disc 10 when the laser beam with the erasing power is irradiated. If the RF component is not included, the first recording (recording on the unrecorded portion) is performed. If the RF component is included, it can be determined that the recording is for the second time or later (recording on the recorded part). Alternatively, it is also possible to record data about the recording status in a predetermined area of the optical disc 10 and read this data to determine whether the recording is the first recording or the second recording.

  FIG. 6 shows another processing flowchart of the present embodiment. When the optical disk 10 is loaded, the system controller 32 reads the optical disk information stored in the lead-in area of the optical disk 10. The lead-in area of the optical disc 10 includes an optimum erasing power Pe1 and an optimum recording power Po1 data set 10a to be used at the time of the first recording as shown in FIG. 7A, and an optimum erasing power Pe to be used at the second and subsequent recordings. The data set 10b of the optimum recording power Po is recorded, and the system controller 32 acquires these information and stores it in the memory (S201). Here, Pe1> Pe and Po1 = Po.

  Next, when data is recorded in the user data area of the optical disc 10, it is determined whether or not it is the first recording (S202). If it is the first recording, (Po1, Pe1) is read from the memory, the recording power is set to Po1, the erasing power is set to Pe1, and data is recorded (S203, S204). In the second and subsequent recordings, (Po, Pe) is read from the memory, the recording power is set to Po, and the erasing power is set to Pe (S204, S205).

  The data to be recorded in the lead-in area of the optical disc 10 is not the data set 10a, 10b of the erasing power and recording power as shown in FIG. 7A, but the data 10a of the erasing ratio ε1 to be used at the time of the initial recording as shown in FIG. 7B. The data 10b of the erasing ratio ε to be used for the second and subsequent recordings may be used.

  In the present embodiment, the erasing power at the first recording (recording on the unrecorded part) is increased more than at the second and subsequent recordings (recording on the recorded part), thereby increasing the erasing ratio at the first recording. However, as described above, the erasing power at the first recording may be increased and the recording power at the first recording may be decreased. In this case, for example, the optimum recording power Po is set by OPC, the optimum erasing power is set by multiplying Po by a predetermined erasing ratio ε, and then recording is performed by multiplying Po by a predetermined coefficient J (J <1) at the first recording. The recording power may be set to K · Pe by setting the power to J · Po and multiplying Pe by a predetermined coefficient K (K> 1). However, J · Po> K · Pe. Alternatively, Po1 <Po in FIG. 7A.

  In this embodiment, as shown in FIG. 3, the erase ratio after the second recording is the same. However, as long as the erase ratio of the first recording is increased with respect to the erase ratio of the second recording, the second and subsequent erases are performed. The ratio may be arbitrarily changed.

1 is a configuration block diagram of an optical disc device in an embodiment. It is explanatory drawing which shows the positional relationship of the mark at the time of the recording strategy and the time of the first time recording, and the second time recording. It is a graph which shows the relationship between the frequency | count of recording and an erasure | elimination ratio. It is a graph which shows the relationship between erasing power and jitter. It is a processing flowchart of an embodiment. It is another process flowchart of embodiment. It is explanatory drawing of the data recorded on an optical disk. It is another data explanatory drawing recorded on an optical disk.

Explanation of symbols

  10 optical disc, 16 optical pickup (PU), 32 system controller, 100, 200 recording mark at the first recording, 300-500 recording mark at the second recording.

Claims (8)

An optical disk device for recording data on a rewritable optical disk,
Data recording means for recording data by superimposing recording power on erasing power;
When the area to be recorded on the optical disc is an unrecorded area, control means for increasing the ratio of the erasing power to the recording power as compared to the recorded area;
An optical disc apparatus comprising: The apparatus of claim 1.
The optical disc apparatus characterized in that the control means increases the erasing power when the area to be recorded on the optical disc is an unrecorded area as compared with the case where the area is an already recorded area. The apparatus of claim 1.
The optical disc apparatus, wherein when the area to be recorded on the optical disc is an unrecorded area, the control means increases the erasing power and reduces the recording power as compared with the case where the area is a recorded area. The apparatus of claim 1.
The control means changes the recording power in the test area of the optical disc, trial writes the test data, and sets the optimum recording power and optimum erasing power set based on the reproduction signal quality obtained by reproducing the test data. On the other hand, when the area to be recorded on the optical disk is an unrecorded area, the optimum erasing power is increased. The apparatus of claim 1.
The control means test-writes test data by changing the recording power in the test area of the optical disc, and for the optimum recording power set based on the reproduction signal quality obtained by reproducing the test data, the control means When the area to be recorded on the optical disk is an unrecorded area, the erasing power is set by multiplying by a predetermined coefficient ε1, and when the data to be recorded on the optical disk is an already recorded area, a predetermined coefficient ε (0 <ε An optical disc apparatus characterized in that the erasing power is set by multiplying <ε1 <1). An optical disk device for recording data on a rewritable optical disk,
Data recording means for recording data by superimposing recording power on erasing power;
Control means for increasing the erasing power as compared with the second and subsequent recordings at the time of initial recording on the optical disc;
An optical disc apparatus comprising: The apparatus of claim 6.
The optical disc apparatus characterized in that the control means increases the erasing power and reduces the recording power at the time of the first recording as compared with the second and subsequent recordings. A rewritable optical disc in which data is recorded by laser light emitted from an optical disc device and recording power superimposed on erasing power,
Information on erasing power at the first recording and erasing power at the second and subsequent recordings is recorded in a predetermined area, and the erasing power at the first recording is larger than the erasing power at the second and subsequent recordings .

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